We think this chick is a hen, due to the small comb. She's a mix of Barred Rock and ...something. We're calling her "Barred What" or "Not Rock" for now. I love the delicate feather pattern.

We keep some cinder blocks on bare earth, and flip them over to reveal tasty (in a chicken's opinion) worms underneath! Probably a rooster: well-developed comb and wattles, and a hint of iridescent green on the tail.
Boy or girl? I'm still not sure!